Sometimes more information is needed to determine the internal condition of trees. Treecall Consulting has a range of equipment that can be used to determine appropriate tree management recommendations.
PiCUS Sonic Tomograph
The PiCUS Sonic Tomograph is an instrument for the detection of dysfunction, decay and cavities in standing trees. Nails are driven through the bark, in a horizontal plane around the circumference of a tree, and attached to sensors. The sensors measure time taken for sound waves to reach from one sensor to each of the other sensors.
A portable computer receives this information and displays a cross section of the trunk showing the variations in speed of the sound waves in different colours. The longer the wave takes to travel between sensors the more decayed or damaged the wood or more of an obstruction is present along that path. A brown or buff colour indicates good quality wood with insignificant strength loss. Purple, Blue and white colours indicate progressively greater decay or dysfunction, leading to hollows at the white end of the spectrum. The green colours indicate wood of intermediate characteristics. Here there is likely to be some incipient decay, or the beginning of alterations to wood characteristics.
The Resi-PD 500 is a microdrill designed to record the resistance of wood to the passage of its drill through a trunk or branch. The drill bit is driven into the wood at the chosen points where information is needed about wood strength.
Regions of sound wood show high resistance to the forward motion of the drill bit, and this information is recorded by a stylus trace onto wax paper. As the drill enters a decayed region the resistance to the forward force is reduced and a lower level of trace is recorded on the wax paper.
Different trees have different strength characteristics and trees of different levels of health also show a variation in characteristics. Where decay has weakened wood the resistance to the drill is reduced and this information is helpful in determining appropriate management operations for a tree.
The basis underlying chlorophyll fluorescence analysis is that light energy absorbed by chlorophyll molecules in a leaf can undergo one of three outcomes: it can be used to drive photosynthesis (photochemistry), excess energy can be dissipated as heat or it can be re‐emitted as light (chlorophyll fluorescence). These three processes occur in competition with each other so that any increase in the efficiency of one will result in a decrease in the yield of the other two. Therefore, by measuring the yield of chlorophyll fluorescence, information about changes in the efficiency of photochemistry and heat dissipation can be achieved.
Treecall Consulting takes chlorophyll fluorescence readings using a small hand held device called the ‘Pocket Pea’ produced by Hansatech. This instrument works by illuminating a dark adapted leaf with a very bright red LED typically for 1 second and recording the chlorophyll fluorescence signal that is emitted during this illumination.
Current research suggests that chlorophyll fluorescence can be used to measure plant vitality and future growth potential. Chlorophyll fluorescence values (Fv/Fm) between 0.85-0.75 indicate a healthy plant and ‘normal’ growth, representative of the species. Values between 0.75-0.65 indicate a plant under some form of stress with a tree showing leaf necrosis and 10% reduction in growth. Values between 0.65-0.45 indicate a plant under moderate-severe stress with a tree showing leaf necrosis and a 30-50% reduction in growth. Values between 0.45-0.25 indicate a plant under severe stress with a tree showing severe leaf necrosis and 50-75% reduction in growth. Values less than 0.25 indicate a plant that is likely to die with a tree showing signs of leaf drop and cessation of growth.
The air spade is a tool that enables the soil surrounding trees to be removed without damaging roots.
Compressed air is directed onto the soil which is blown away from the root surface. This method avoids inadvertent damage from spades or other hand tools and allows the tree root structure or decayed areas to be inspected or for underground services or foundations to be installed without the need for severing roots.
This method is also used where poor quality or contaminated soil is to be replaced with better quality material to encourage healthy tree growth.